One of the key problems in modern materials science is the creation of new functional materials with improved optoelectronic and operational properties that can be purposefully changed depending on the field of their application. This is possible with the use of nanostructured multicomponent materials combining the unique properties of nanoobjects of different nature, such as ultra-thin two-dimensional nanomaterials (for example, graphene), metallic nanoparticles, and semiconductor nanocrystals. Semiconductor nanocrystals with electronic transitions in the near-infrared spectral range are promising materials for many applications, such as solar energy, telecommunications systems, and biomedicine.
Within the framework of our research projects we study PbS quantum dots with optical transitions in the spectral range of 0.8–2.0 µm. These quantum dots possess some unique properties, such as efficient multi-exciton generation, large static dielectric constants, highly symmetrical sodium chloride structure, and narrow fundamental bandgaps. Small and equal masses of the charge carriers and large Bohr radius (18 nm) let one use PbS quantum dots as a model object for investigation of the strong quantum confinement regime. PbS quantum dots of different sizes demonstrate unusual optical properties, namely, large Stoke shift and surprisingly long photoluminescence decay times. Moreover, they possess anomalous size dependence of their photoluminescence lifetimes, which has never been reported for other semiconductor quantum dots. Another interesting and perspective feature of these quantum dots is the ability to easily form ordered 2D and 3D structures, named superlattices and supercrystals. Such structures are based on a self-organization process and may become a new platform for high-performance solar cells and light detectors.
Research group: Alexander Baranov, Petr Parfenov, Elena Ushakova, Alexander Litvin, Yulia Gromova